Basil,
make sure you go to start> Settings>control panel> Sounds and audio
Make sure you have the asio device selected in the audio tab. Under recording, the microphone should be selected and you should be able to set the volume there.
use the windows settings first then if your audio card has it's own mixer, you may be able to control it there.
Let us know your laptop ,model and sound card that is included.
Nick